Salt Loading Aggravates the Relationship between Melatonin and Proteinuria in Patients with Chronic Kidney Disease

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Author(s)

    • Ohashi Naro
    • Internal Medicine 1, Hamamatsu University School of Medicine, Japan
    • Ishigaki Sayaka
    • Blood Purification Unit, Hamamatsu University School of Medicine, Japan
    • Isobe Shinsuke
    • Internal Medicine 1, Hamamatsu University School of Medicine, Japan
    • Sato Taichi
    • Internal Medicine 1, Hamamatsu University School of Medicine, Japan
    • Tsuji Takayuki
    • Internal Medicine 1, Hamamatsu University School of Medicine, Japan
    • Kato Akihiko
    • Blood Purification Unit, Hamamatsu University School of Medicine, Japan
    • Yasuda Hideo
    • Internal Medicine 1, Hamamatsu University School of Medicine, Japan

Abstract

<p><b>Objective </b>Salt loading induces renal damage independently of blood pressure (BP) elevation via reactive oxygen species and sympathetic activity. Melatonin, a hormone that regulates the circadian rhythm, has multiple functions, including anti-oxidant effects and the inhibition of sympathetic activity. We have shown that impaired melatonin secretion is associated with renal damage in chronic kidney disease (CKD) patients. However, the associations between salt loading, melatonin secretion, and urinary albumin and protein have not been clarified. </p><p><b>Methods </b>We recruited 32 CKD patients, conducted 24-hour ambulatory BP monitoring and collected daytime and nighttime urine while the patients were consuming a standard salt (10 g/day) or low salt (6 g/day) diet. The excretion levels of albumin, protein and 6-sulfatoxymelatonin (aMT6s), a metabolite of melatonin, in daytime and nighttime urine were investigated in patients consuming standard salt and low salt diets. </p><p><b>Results </b>The urinary aMT6s levels in daytime and nighttime of the patients consuming standard salt and low salt diets did not differ to a statistically significant extent. However, the urinary aMT6s levels in patients consuming a standard salt diet-but not patients consuming a low salt diet-were significantly and negatively correlated with the daytime and nighttime urinary albumin and protein levels. Contrarily, no significant correlations were found between the urinary aMT6s levels and the BP levels, renal function, and plasma angiotensin II levels in patients consuming either a standard salt or low salt diet. A multiple regression analysis adjusted for age, sex, and body mass index revealed that the urinary albumin and protein levels were significantly and negatively associated with the urinary aMT6s levels in patients consuming a standard salt diet, but not in patients consuming a low salt diet. </p><p><b>Conclusion </b>Salt loading aggravates the relationship between melatonin secretion and albuminuria or proteinuria. </p>

Journal

  • Internal Medicine

    Internal Medicine 58(11), 1557-1564, 2019

    The Japanese Society of Internal Medicine

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